The account that I have setup for myself has started to bounce messages b/c my quota has been reached. I am using Thunderbird as a POP3 client. I do not have it set to leave messages on the server, but when I login to webmail, I see that messages that are in my Thunderbird Inbox are now in the trash on the server.

Is this a Zimbra thing, to move popped mail to the trash? I could set the trash lifetime of messages, but a high traffic account would have to have a low lifetime. Then if the owner of that account used the webmail interface, they would see all their popped email in the trash and become confused. That would then result in more trouble tickets, etc. basically something I don't want to have to explain to everyone using the server.